Hitherto, it has been proposed to provide a filter for a smoking article such as a cigarette, from a cellulose acetate tow wrapped in a plug wrap and attached to a rod of smoking material such as tobacco, by means of tipping paper which overlaps both the filter and the end of the rod. Smoke is drawn from the tobacco rod end of the filter to its mouth end when a smoker inhales smoke from the cigarette. It has been proposed to dilute the smoke inhaled by the smoker, by forming ventilation holes in the filter to allow outside air to pass laterally into the filter material and dilute the flow of smoke to the user. However, a problem with such an arrangement is that the user may place their fingers over the ventilation holes and reduce the flow of ventilation air. Several proposals have been made to overcome this difficulty. For example, U.S. Pat. No. 4,718,436 discloses a tipping paper arrangement in which lateral ventilation channels are formed.
The present invention provides an improved way of admitting ventilation and air into the filter which is less complex to construct and can readily be accommodated within the smoking article manufacturing process.